Diving fin

ABSTRACT

Disclosed is a diving fin, securable about a swimmer&#39;s ankle, having a blade oriented at a propulsive angle independent of how the swimmer&#39;s toes are positioned. The blade can be positioned not to interfere with walking and wading. The blade and boot are lockably engageable, and are then rotatable to a locked deployed position wherein the blade projects past the swimmer&#39;s heel and in line with the swimmer&#39;s lower leg. In one embodiment, the blade has a connector and the boot has a hub lockably engageable therewith to attach or detach the blade. Thus, the boot can be worn without the blade. The engaged connector is upwardly rotatable behind the swimmer&#39;s leg. A strap secures the undeployed blade adjacent the leg. The connector is rotatable between the undeployed and deployed positions and is lockable in the deployed position. In one embodiment, the blade can wobble a few degrees when in the locked position. Releasable locking mechanisms are disclosed for keeping the blade attached to the boot and for limiting the orientation of the blade relative to the boot. Fasteners are disclosed for holding the blade in the undeployed position by its trailing end portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to swim fins, more particularly tohigh-performance diving fins and especially to fins for shore diving andamphibious activities.

2. Previous Art

As even the best swimmer knows, the human leg and foot are almostuseless for propulsion in water. While the foot is an elegant adaptationfor walking, it is blunt, stiff and naturally oriented at a right angleto the lower leg. By kicking harder, a swimmer actually wastes effortand increases drag. To recapture some of the aquatic performance thatwas sacrificed eons ago as the price of terrestrial evolution, swimmerswear fins. However, fins are clumsy on land and their propulsiveeffectiveness is limited by the configuration of the human knee andankle, which make it difficult to angle the fin properly.

The angle of a fin is important because the fin propels the swimmer byimparting momentum to a mass of water, such that the swimmer gains equalmomentum--and is moved--in the opposite direction. Generally, as theswimmer kicks, each fin reciprocates, its upper and lower surfacesalternately pressing against the water. Such reciprocation alone wouldonly stir the water. However, because the fin bends, when a fin surfaceis pressing into the water, it is usually also facing at least partiallytoward the rear. Thus, during a complete stroke, the fin imparts a netrearward momentum to the water and the swimmer is correspondinglypropelled forward.

The kicking movement employed by swimmers and divers can be describedwith reference to a starting position in which the leg is straight atthe knee and in line with the long axis of the spine. First, thequadriceps relaxes and the hip flexor begins to contract. The hip flexorcontraction moves or flexes the upper leg forward at the hip. Therelaxation of the quadriceps allows the knee to bend as the upper legmoves forward. Once the knee has moved forward, contraction of thequadriceps straightens the leg at the knee, causing the foot and the finto move forward. The bending at the knee orients the dorsal surface ofthe foot and therefore the dorsal surface of the fin blade at an angle,which imparts a rearward momentum to the water, propelling the swimmerforward.

Swimmers and divers employ two common kicking movements: the flutterkick and the undulating (or butterfly, or dolphin) kick. In the flutterkick, one leg flexes while the other leg extends. With this kickingmovement, the weaker direction of movement (upper leg extension) willlimit the muscles involved in the stronger direction of movement (upperleg flexion followed by lower leg quadriceps extension) to the levels offorce established by the extension muscles, because the kicking movementmust remain balanced. Much drag is created as the legs work against eachother. In the undulating kick, both legs move in the same direction.Flexion at the hip is followed by contraction of the quadriceps tostraighten the lower leg at the knee. Hamstring and gluteal contractionfollow to extend the legs back to the starting position. The undulatingkick usually involves greater angles of movement than the flutter kick.

Because conventional fins extend in the general direction of the toes,the fin angle depends on the angle of extension of the foot, which islimited to the range of motion of the ankle joint. During the returnstroke, the swimmer can extend the foot and point the toes in order toangle the plantar (foot bottom) surface of the fin aft for fairlyefficient propulsion. All too soon, however, the upper leg reaches thelimit of its rearward motion and it is time to bring the leg forward andbend the knee in preparation for the next kick stroke. As the knee isbent and brought forward, the thigh, calf and heel create drag.

During the kick stroke, the powerful quadriceps muscle can be applied.However, most people's feet will not extend (point downward) far enoughto place the fin at a propulsive angle during the whole kick stroke.This problem is only partly remedied by the flexibility of the fin.While flexibility can enable the distal portions of the fin surface toassume a propulsive angle after kicking force is applied, this flexingoccurs only after significant energy has been wasted and leaves theproximal portion of the fin at an angle which produces much drag andlittle propulsion.

Even more seriously, the ligaments of the human ankle are too weak towithstand the full kicking force of the quadriceps driving a large finin water. Swimmers who deliberately kick with full force while wearing alarge fin will incur severe damage to their ankle ligaments. There areestimates that the quadriceps can generate up to three times the kickingforce that the ankle ligaments can safely deliver to a large fin. Thus,a need exists to more quickly and more efficiently orient the fin at theideal propulsive angle, especially during the kick stroke. A need alsoexists to couple the powerful kick of the quadriceps to a large divingfin without overloading the ligaments of the ankle.

Another difficulty with fins is encountered at the beach. Fins areclumsy for walking on any surface, even more so in shallow water, andespecially in currents. The muscles that elevate the human foot are veryweak and are no match for the power of the sea against a long SCUBA fin.Surf pounding against a long fin will easily trip and upset a wadingdiver. Although the diver may carry the fins into calm water and thenput them on, the fins must be worn when entering surf, for a finlessdiver is a helpless diver and will be driven back onto the beach by evenmoderate waves. The results may be merely frustrating or they may be farmore serious, depending on how urgently the diver needs to move along.

Divers would benefit were they able to walk, or even run, into shallowsurf with their fins attached, but positioned so as not to interferewith foot placement. Particularly advantageous would be a way ofattaching a fin to the lower leg and orienting the fin upward, adjacentthe lower leg, and then quickly deploying the fin in a propulsiveposition once the water is deep enough for the fins to function. What isespecially needed is a swim fin which allows a diver to wade againstwaves or surf in shallow water, which can be deployed quickly in thetransition from wading to swimming, which is oriented at a propulsiveangle during the kick stroke as well as the return stroke, and whichenables the diver to kick powerfully yet comfortably and safely.Additionally, a swimmer whose foot is injured, malformed, or for anyother reason cannot bear the forces that attend the use of aconventional diving fin would benefit from such an innovation.

SUMMARY AND OBJECTS OF THE INVENTION

It is an object of the present invention to provide a fin, which enablesa swimmer to derive efficient propulsion from leg movement, andespecially from contraction of the powerful quadriceps muscle, withoutsustaining injury to the ligaments of the ankle.

It is an additional object of the present invention to provide a fin,which facilitates a swimmer's entering and leaving shallow water at abeach or shoreline.

It is an additional object to provide such a fin, which is suitable forsprinting across a beach, plunging into surf, and rapidly deploying thefin without stopping to put the fin on.

It is an additional object to provide such a fin, which is substantiallyself-deploying when, released from the stowed position.

It is an additional object to provide such a fin, which can be worn by aperson having an injured, malformed or missing foot.

In accordance with the aforementioned objects and those that will bementioned and will become apparent below, a diving fin according to thepresent invention comprises:

a fin blade;

a boot for coupling the fin blade to the swimmer, the boot having a top,a bottom, a front, a back, a medial side and a lateral side, a bootlongitudinal axis being defined by a line passing through the top andbottom substantially parallel to the back and the sides;

the fin blade being attachable to the boot;

the boot being capable of positioning the attached fin blade parallel tothe boot longitudinal axis;

whereby the fin blade is held to the boot proximate the swimmer's ankleand projects past the swimmer's heel in line with the swimmer's lowerleg, enabling the swimmer to kick powerfully and efficiently withouthyperextension of the foot.

In an exemplary embodiment of a diving fin according to the presentinvention, the fin blade is detachable from the boot. This permits theswimmer to walk in the boot without the blade and attach the blade whilewearing the boot.

In another exemplary embodiment of a diving fin according to the presentinvention, a standing swimmer can attach the blade from above and behindthe boot and secure the blade end adjacent the back of the swimmer's legfor walking, wading or even sprinting a short distance. Once in thewater, the swimmer can quickly free the blade end, rotate the blade downpast the heel and lock it in line with the swimmer's lower leg. Thisallows a fast transition between land and water. With the blade alreadyprojecting from the boot in line with the lower leg, the swimmer doesnot need to point the toes of the foot in order to place the blade at apropulsive angle. The diving fin includes a locking mechanism, whichfixes the blade in the propulsive position. In a preferred embodiment ofa diving fin according to the present invention, such a lockingmechanism is disposed on the ankle portion of the boot.

In another exemplary embodiment of a diving fin according to the presentinvention, a hub on the boot lockably engages a connector on the finblade, facilitating quick attachment and detachment of the blade. In apreferred embodiment, a spindle on the connector engages a bore in thehub and a pin projects from the spindle into the bore, keeping thespindle aligned with the bore. The pin is manually releasable to allowthe connector to be removed from the hub. In another exemplaryembodiment, the hub is circular and is covered by a circular cap. Agroove runs from the bore to the hub periphery and the cap has arestricted slot paralleling that of the hub and permits the matchingprofile of the spindle to slide from the periphery to the bore. The capconfines the spindle within the groove except at the periphery.

In yet another preferred embodiment, the cap periphery overhangs the hubperiphery and the connector includes a key, which curls around the capperiphery toward the hub periphery. As the connector is rotated relativeto the hub, the spindle centering pin in the bore restricts motion ofthe key to a circular arc following the periphery. The key stabilizesthe connector, distributing torsional stresses away from the spindle tothe cap via the key, which is trapped on the cap periphery.

In yet another preferred embodiment, a deployment lock is movablydisposed on the ankle portion of the boot and is biased against the hubperiphery. As the connector is rotated into the deployed position, thekey urges the lock aside and enters a notch in the lock, whereupon thelock closes against the hub periphery and traps the key, limiting therange of rotation of the spindle. This holds the blade in the deployedposition. In still other preferred embodiments, the notch and key aredimensioned to allow a small range of motion, enabling the blade toreach a new propulsive angle shortly after a reversal of the forceapplied to it by the swimmer.

Another exemplary embodiment of a diving fin according to the presentinvention has a pair of connectors attaching the blade to a pair of hubslocated on the sides of the ankle portion of the boot. The connectorsare lockably and rotatably attachable to the hubs and are lockable inthe deployed (propulsive) position. Retaining straps hold the bladesagainst the back of the leg when undeployed. In a preferred embodimentof a diving fin according to the present invention, the hubs andconnectors include the mechanisms that lock the blade to the boot andfix the blade in the deployed position.

Also in accordance with the above objects and with those that will bementioned and will become apparent below, a diving fin in accordancewith the present invention comprises:

a fin blade;

a boot for coupling the fin blade to the swimmer, the boot having a top,a bottom, a front, a back, a medial side and a lateral side, a bootlongitudinal axis being defined by a line passing through the top andbottom substantially parallel to the back and the sides;

the fin blade being attachable to the boot;

the boot holding the attached fin blade in an orientation substantiallydependent upon the orientation of the boot,

whereby the blade is oriented independently of the elevation andextension of the swimmer's toes and the swimmer is able to kickpowerfully and efficiently without hyperextension of the foot.

In other exemplary embodiments of a diving fin according to the presentinvention, the boot, blade, hub and connector function as set forth forthe previously mentioned embodiments. Various other aspects of thepresent invention are set forth below.

Also in accordance with the above objects and with those that will bementioned and will become apparent below, a diving fin prosthesis for aswimmer having an injured, malformed or missing foot in accordance withthe present invention comprises:

a fin blade;

a boot for coupling the fin blade to the swimmer's lower leg, the bootbeing securable about the distal regions thereof;

the fin blade being attachable to the boot;

the boot being capable of positioning the attached fin blade parallel tothe swimmer's lower leg;

whereby the fin blade is held to the boot proximate the distal portionof the swimmer's lower leg and projects therefrom in line with theswimmer's lower leg, enabling the swimmer to kick powerfully andefficiently without having a foot to which a conventional diving finwould be secured.

An advantage of the present invention is that the deployed blade is notcoupled to the toe portion of the swimmer's foot. Thus, the swimmer'sankle ligaments do not have to bear all the kicking force that istransmitted to the blade. Rather, the blade projects from a boot coupledabout the ankle and about portions of the lower leg and the footadjacent thereto, so that the boot distributes forces over the swimmer'sinstep, heel, ankle, and lower leg.

Another advantage of the present invention is that the blade is capableof reaching a propulsive angle during the kick stroke whether or not theswimmer's toes happen to be extended (pointed down, as when the calfmuscles are fully contracted).

Another advantage of the present invention is that with the blade in theundeployed position the swimmer can wade, walk, and even sprint,activities difficult or impossible when wearing conventional fins.

Another advantage of the present invention is that the attached blade israpidly deployable.

Another advantage of the present invention is that the blade is quicklyattachable to the boot and quickly detachable therefrom.

Another advantage is that the benefits of high-performance diving finsare made available to swimmers whose feet are injured, malformed ormissing.

BRIEF DESCRIPTION OF THE DRAWING

For a further understanding of the objects and advantages of the presentinvention, reference should be given to the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like parts are given like reference numerals and wherein:

FIG. 1 is a perspective view of an exemplary embodiment of a diving finaccording to the present invention.

FIG. 2 is a side view of an exemplary embodiment of a diving finaccording to the present invention illustrating a deployed and anundeployed position.

FIG. 3 is an exploded perspective view of portions of a mechanism forfacilitating the exemplary fin blade to go from the deployed to theundeployed position.

FIGS. 4 and 5 are partial front sectional views of the exemplaryembodiment shown by FIG. 3.

FIGS. 6 through 9 are partial side views of the ankle and connectorportions of the mechanism for facilitating the exemplary embodiments ofthe diving fin according to the present invention to go from thedeployed to the undeployed position.

FIG. 10 illustrates an exemplary embodiment of the diving fin accordingto the present invention in use.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described with reference to FIG. 1, whichillustrates a side perspective view of an exemplary embodiment of adiving fin according to the present invention. The diving fin comprisesa fin blade 20 having a leading edge 22, a trailing edge 24, a medialedge 26, a lateral edge 28, a top surface 30 and a bottom surface 32.For purposes of description, the forward direction is defined as beingfrom the trailing edge 24 to the leading edge 22 as shown by the arrow34. Also for purposes of description, a blade longitudinal axis 36 isdefined by a line intersecting the leading edge 22 and the trailing edge24. Similarly, a blade transverse axis 38 is defined by a lineintersecting the medial edge 26 and the lateral edge 28 and intersectingthe blade longitudinal axis 36 at a right angle. The medial and lateraledges 26 and 28 of the fin blade 20 project forward of the leading edge22 to form rail-shaped medial and lateral connectors 40 and 42. Eachconnector 40 and 42 has a distal end portion 44 and 46 including amating end 150.

The fin blade 20 has a length of approximately 16 to 24 inches and awidth of approximately to 8 to 12 inches. The fin blade 20 is formed ofpolypropylene or another suitably rigid material. The fin blade has astiffening rib running down each edge, tapering from about 1.75 inchesnear the portion that fits the diver's foot to about 0.5 inch at thedistal end of the blade.

With continued reference to FIG. 1, a boot 50 is disposed about aswimmer's foot, ankle and lower leg. The boot 50 has a front 52 definingan opening, which encircles the arch and the instep of the swimmer'sfoot. The boot 50 has a back 54 covering the swimmer's heel, Achilles'tendon and lower calf muscle; a top 56, which encircles the swimmer'sshin and calf; a bottom 58 covering the heel end of the sole of theswimmer's foot; a medial side 60 including a medial ankle portion 62covering the medial surface of the swimmer's ankle joint; and a lateralside 64 including a lateral ankle portion 66 covering the lateralsurface of the swimmer's ankle joint. A hub 70 is affixed to each ankleportion 62 and 66.

It will be appreciated that the invention is not limited to the abovedescribed boot portion. The boot 50 need not cover any particularportion of the lower leg. In some embodiments, it may be advantageousthat the boot 50 extends well up gastrocnemius (calf muscle) withstrapping up high on the shin to adequately distribute forces overenough tissue surface area. Compression and shear forces must bedistributed over enough area so the tissue does not fail. It is believedthat, in fact, the boot may extend to just below the user's knee withsuccessful operation of the diving fin.

With continued reference to FIG. 1, there is shown, the boot having aboot transverse axis 72 being defined by a line passing between the hubs70. Similarly, the boot has a longitudinal axis 74, which is defined bya line intersecting the boot transverse axis 72 at a right angle andbeing roughly parallel to the back 54 of the boot 50. In use, FIG. 10, aswimmer wears the boot so that the boot longitudinal axis 74 isgenerally aligned with the swimmer's tibia and fibula and the boottransverse axis 72, and in general passes through the swimmer's medialand lateral malleoli and is generally aligned with the axis of elevationand extension of the swimmer's foot about the ankle joint. A fastenerassembly 76 (FIG. 2) secures the boot 50 to the swimmer. The fastenerassembly 76 completes the front 52 of the boot and may be closed bymeans of clasping, hooking, knotting, buckling and the like. The front52, back 54, bottom 58 and sides of the boot 50 are reinforced asappropriate to comfortably and firmly stabilize the boot 50 on theswimmer. FIG. 1 depicts the fin blade 20 positioned above and behind theboot 50 with the fin blade connectors 40 and 42 angled downward andforward and pointing toward the hubs 70.

Referring also now to FIG. 2, from the direction shown in FIG. 1 eachconnector 40 and 42 is insertable into a hub 70 as indicated by thearrows 78. Once inserted, the connector 40 locks into the hub 70 andcannot be detached until unlocked from the hub 70, as is set forth indetail with reference to FIGS. 3 and 4. While inserted and locked intothe hub 70, the connector 40 is freely rotatable from an undeployedposition (arrow 80) toward a deployed position (arrow 82). As isemphasized with reference to FIGS. 6 through 8, this freedom of rotationserves the critically important objective of protecting the swimmer fromdrowning. When the connector 40 reaches the deployed position 82, itlocks in the deployed position 82 until unlocked, as is set forth indetail with reference to FIGS. 6 through 9.

With continued reference to FIG. 2, in use a swimmer puts the boot 50 onand secures the fastener assembly 76. The swimmer may then walk in theboot 50 without attaching the blade 20 (FIG. 10). Alternatively, theswimmer may insert the fin blade connector 40 into the hub 70 and securethe trailing edge 24 of the fin blade 20 adjacent the back of theswimmer's leg, (FIG. 10) as is set forth in detail with reference toFIGS. 3 through 5. In this undeployed position 80, the fin blade 20 doesnot interfere with the acts of standing and walking. Because theundeployed fin blade 20 does not project forward beyond the swimmer'stoes as does a conventional diving fin, it is unlikely to trip theswimmer or to apply large forces to the swimmer's foot when the swimmerstands in swiftly moving shallow water. Indeed, the swimmer may walkrapidly or even run a moderate distance--something not to be attemptedwith conventional diving fins. Because the trailing edge 24 of the finblade 20 is doubled back toward the swimmer's knee, it is shielded fromthe current and has minimal leverage over the swimmer's leg.

Importantly, the fin blade 20 is held at the angle of the undeployedposition 80 only at or near its trailing--distal--end 24 and not at ornear the connector 40. If the connector 40 were allowed to lock at afixed upward-projecting angle with the trailing edge 24 free, there is adanger that the swimmer's normal kicking motions would propel theswimmer in an unexpected direction. This would surprise the swimmer andcould lead to unpleasant circumstances. For this reason, in a preferredmode of carrying out the invention, the hubs 70 are not capable oflocking at any angle other than that of the deployed position 82. Thismode is strongly recommended.

Referring to FIG. 1, a first restraining strap 84 extends from the finblade 20 were the trailing edge 24 meets the medial edge 26. A secondrestraining strap 86 extends from the meeting of the trailing andlateral edges 24 and 28. The straps 84 and 86 are attachable by means ofeyelets or slots (85 and 87) located within approximately 200millimeters of the trailing edge 24 of the fin blade 20. The first strap84 is covered with VELCRO wool, the second, 86, with VELCRO hooks. Theswimmer adjusts the fin blade connector 40 to the undeployed position,brings the straps 84 and 86 together about his or her leg, and joins thestraps 84 and 86 to hold the fin in the undeployed position. It will benoted that the fin blade 20 is flexible enough to wrap around the backof the swimmer's leg. Thus, the straps 84 and 86 need not be more than afew inches long. Importantly, the trailing edge 24 of the fin blade 20is held adjacent the back of the swimmer's leg or nearly so, and thuswill not propel the swimmer downward unexpectedly. When ready to deploythe fin blade 20, the swimmer pulls the straps 84 and 86 apart. Variousother connections may be envisioned.

In an alternative embodiment, instead of straps, the fins may berestrained by cords 88 and 90 having quick-release pin-and-socket typeconnecting ends 92 and 94. Optionally, each cord 88 and 90 is elastic.Optionally, each cord 88 and 90 is retractably disposed in a tubularcanal 96 in the medial or lateral edge 26 or 28 of the fin blade 20.Thus, only the connecting end 92 or 94 is exposed until the cord 88 or90 is grasped and stretched by the swimmer. This reduces the drag andthe possibility of entanglement while swimming. In use, the swimmeradjusts the fin blade 20 to the undeployed position, brings the firstand second connecting ends 92 and 94 together about the leg andinterlocks them to hold the fin blade 20 adjacent the back of the leg.

To deploy the fin, the swimmer disconnects the connecting ends 92 and94, whereupon the cords 88 and 90 retract within the canals 96 and thefin blade 20 may rotate toward the deployed position 82.

As can be understood with reference to FIGS. 2 and 10, the swimmer mayrun, walk or crawl to a point where the water is deep enough to beginswimming. The swimmer may then release the trailing edge 24 of the finblade 20 and, with moderate kicking motion, let the fin blade 20 rotateinto the deployed position 82. When the swimmer feels the fin blade 20locking into the deployed position 82, the swimmer knows the blade 20 isready for propulsive use and may begin kicking vigorously.

Referring still to FIGS. 1 and 2, the boot 50 for this exemplaryembodiment of a diving fin according to the present invention isstabilized relative to the swimmer's ankle and lower leg. In contrast, aconventional diving fin is stabilized relative to the swimmer's foot.The front 52, back 54 and sides of the boot 50 are stiff enough andsecured tightly enough that, when the swimmer kicks, the boot 50 cannotwobble or rotate enough to abrade or bruise the swimmer. The fin blade20 in the deployed position 82 projects beneath the swimmer's heel,roughly in line with the swimmer's tibia and fibula. Thus, when theswimmer kicks, the fin blade 20 is already at or close to a propulsiveangle relative to the swimmer's lower leg. Importantly, the swimmer'sfoot does not have to be plantar flexed (i.e., the swimmer does not haveto point his or her toes down in line with the lower leg) in order forthe fin to attain a propulsive angle during the kick stroke. Thus, theswimmer may kick at maximum strength without straining his ankleligaments. The swimmer's foot may be plantar flexed (i.e., toes pointeddown) either out of habit or for the purpose of reducing drag; however,the swimmer's ankle joint ligaments do not bear the major part of theload during the kick stroke as they do with a conventional diving fin.

Referring back to FIG. 1, it can be seen that a flat platform 100 isaffixed to the ankle portion of the boot 50. The hub 70 is affixed tothe platform 100. The hub 70 is slotted to receive the connector 40 froma direction roughly corresponding to the undeployed position 80 of thefin blade 20.

With reference to FIG. 3, an exploded perspective view details the leftlateral or right medial platform 100 and hub 70 (thus, a mirror image ofFIG. 3 would depict the right lateral and left medial platform 100 andhub 70). The platform 100 includes a platform surface 101 and a centerbore 102 therein which defines a hub axis 104. The center bores 102 ofthe platforms 100 of the medial and lateral ankle portions 62 and 66 ofthe boot 50 are mutually aligned and are also roughly parallel to androughly aligned with the boot transverse axis 72 (see FIG. 1). Thecenter bore 102 has a diameter of approximately 4 millimeters. The hub70 is affixed to the platform 100. The hub 70 has a hub height 105, ahub face 106 and a hub periphery 108. The hub height 105 isapproximately 4 millimeters. The hub periphery 108 describes a circleabout the hub axis 104. The hub periphery 108 has a radius ofapproximately 20 millimeters.

With continued reference to FIG. 3, a linear receiving groove 110 is cutinto the face 106 of the hub 70 and all the way through the hub 70 tothe surface 101 of the platform 100. The receiving groove 110 has agroove width 114 of approximately 12 millimeters, a first groove end 116describing a semicircle having a radius of approximately 6 millimetersabout the hub axis 104 and a second groove end 118 which defines anopening 120 at the hub periphery 108. The receiving groove 110 definesan angle, relative to the boot longitudinal axis 74, corresponding tothe undeployed position 80 of the fin blade 20.

With continued reference to FIG. 3, an indentation 112 is cut into theperiphery 108 of the hub 70. The indentation 112 is approximatelyopposite the receiving groove 110, subtends an angle of approximately50° about the hub axis 104, is cut-in so as to reduce the radius of thehub by approximately 3 millimeters, and is cut to a depth equaling thehub height 105, i.e., all the way from the hub face 106 to the platformsurface 101. The indentation 112 functions as part of the mechanism thatlocks the fin blade 20 in the deployed position 82 as is set forth indetail with reference to FIGS. 6 through 8.

With continued reference to FIG. 3, a deployment lock 122 is rotatablyattached to the surface 101 of the platform 100 between the hub 70 andthe bottom 58 of the boot 50. The deployment lock 122 rotates in a planeparallel to the platform surface 101 about a fastener 144 which islocated proximate the hub periphery 108 and slightly forward of theindentation 112. The deployment lock 122 is generally flat, has a heightapproximating the height 105 of the hub 70 and has an edge 124. The edge124 defines a deployment angle limiting notch 126 flanked by a first arc128 and a second arc 130. The first arc 128, immediately forward of thenotch 126, fits against the indentation 112 in the periphery 108 of thehub 70. The second arc 130, immediately behind the notch 126, fitsagainst the periphery 108 of the hub 70. The notch 126 is linear, has awidth of approximately 5 millimeters, has a length of approximately 12millimeters and is centered on and oriented parallel to a radiusextending from the hub axis 104, parallel to the boot longitudinal axis74, toward the boot bottom 58 (see FIG. 1).

The deployment lock 122 is normally biased toward the hub periphery 108.In this exemplary embodiment, a spring 125 is coiled about the fastener144 and impinges upon the corner portion 142 of the cap 138 and upon thedeployment lock 122. Alternative embodiments may include, for example, aleaf spring adjacent the deployment lock 122. Also alternatively, aspring may be omitted if the deployment lock 122 itself includes anelastic portion.

The angle limiting notch 126 functions as part of the mechanism thatlocks the fin blade 20 in the deployed position 82 as is set forth indetail with reference to FIGS. 6 through 8. The deployment lock 122 alsoincludes a handle portion 132 which projects toward the front 52 of theboot 50 and which is manipulable to rotate the deployment lock 122.

With continued reference to FIG. 3, a cap 134 covers the face 106 of thehub 70. The cap 134 has a height of approximately 4 millimeters, a flatcap face 136 and a cap periphery 138. The cap periphery 138 describes acircle having a radius of approximately 23 millimeters about the hubaxis 104. A receiving slot 140 is cut into the face and all the waythrough the cap 134. The receiving slot 140 is linear, has a width ofapproximately 6 millimeters, a first end 145 describing a semicirclehaving a radius of approximately 3 millimeters about the hub axis 104and a second end 147 which defines an opening 149 at the cap periphery138. The receiving slot 140 is centered directly over and is orientedparallel to the receiving groove 110 of the hub 70. At an angle roughlyopposite the receiving slot 140, the cap periphery 138 extendsapproximately 10 millimeters outside the hub radius to define a cornerportion 142 covering a portion of the deployment lock 122. A fastener144 holds the corner portion 142 approximately the height 105 of the hub70 away from the surface 101 of the platform 100, allowing thedeployment lock 122 to rotate and slide between the corner portion 142and the platform surface 101. The deployment lock 122 rotates about thefastener 144.

With continued reference to FIG. 3, an exemplary fin blade connector 40in accordance with the present invention has a mating end 150. Themating end 150 is roughly rail-shaped and has a flat front side 152. Aspindle 156 projects perpendicularly from the front side 152. Thespindle 156 has a cylindrical stem 158 ending in a cylindrical head 160coaxial with the stem 158. The stem 158 has a height of approximately 4millimeters and a diameter of approximately 6 millimeters. The head 160has a height of approximately 4 millimeters and a diameter ofapproximately 12 millimeters. It can be appreciated that when the stem158 and head 160 are approximated to the receiving slot 140 andreceiving groove 110, respectively, the spindle 156 will engage the cap134, hub 70 and platform 100 and may slide toward the hub axis 104 untilit is positioned directly over the center bore 102.

With reference to FIG. 4, a front sectional view is shown of theplatform 100, hub 70, lock 122, cap 134, and connector 40 that aredepicted in FIG. 3. The mating end 150 has a flattened front side 152and a flattened backside 154. A through-bore 162, coaxial with the stem158 and head 160, completely penetrates the mating end 150 from thefront side 152 to the backside 154. A centering pin 164 is slidablydisposed in the through-bore 162. The centering pin 164 has a nosesegment 166 and a tail segment 168. The nose segment 166 and thethrough-bore 162 are approximately 4 millimeters in diameter. The tailsegment 168 is approximately 2 millimeters in diameter. The tail segment168 projects from the through-bore 162 beyond the back of the mating end150. The through-bore 162 has a restricted opening 170 at the backside154 having a diameter slightly larger than that of the tail segment 168.A helical spring 172 is disposed about the tail segment 168 andcompressed between the nose segment 166 and the restricted opening 170.The spring 172 biases the centering pin 164 toward the front side 152 ofthe mating end 150. A pin release 174 is pivotably attached to the tailsegment 168 of the centering pin 164 outside the through-bore 162 and isabuttingly disposed against the backside 154 of the mating end 150. Thepin release 174 interferes with the restricted opening 170, therebypreventing the centering pin 164 from being ejected from thethrough-bore 162. The centering pin 164 is long enough that the nosesegment 166 projects approximately 4 millimeters beyond the platformsurface 101 into the platform 100 while the pin release 174 remainsaccessible. The pin release 174 has a handle 176, which is operable topivot the release and to withdraw the centering pin 164 from the centerbore 102. With the centering pin 164 withdrawn from the center bore 102,the spindle 156 is free to slide out of the receiving groove 110 andslot 140 at the cap periphery 138, completely detaching the fin blade 20from the boot 50.

With reference to FIG. 5 and also back to FIG. 3, it will be appreciatedthat when the spindle 156 is positioned over the center bore 102, thenose segment 166 of the centering pin 164 will slide into the centerbore 102 and remain there until withdrawn by operation of the pinrelease 174. As long as the nose segment 166 of the centering pin 164 isengaged in the center bore 102, the spindle 156 will be locked in placeand will not slide toward the hub periphery 108.

Referring again to FIGS. 3 and 4, a key 178 projects from the front side152 of the mating end 150 of the connector 40 approximately 23millimeters aft of the through-bore 162. The key 178 has a stem 180. Anarm 182 projects from the stem 180 at a height of approximately 4millimeters from the front side 152 of the connector 40 and extends,parallel to the front side 152, approximately 3 millimeters toward thespindle 156. It will be appreciated that when the spindle 156 is engagedover the center bore 102, the stem 180 and arm 182 of the key 178describe radii barely equal to the cap periphery 138 and hub periphery108. Thus, the key stem 180 and arm 182 barely reach around the capperiphery 138 (which overhangs the hub periphery 108 by approximately 3millimeters) and toward the hub periphery 108. As the fin blade 20 isrotated toward the deployed position 82, the key 178 becomes trappedbetween the cap periphery 138 and the platform surface 101 and can onlyslide around the periphery.

With reference to FIGS. 6 through 9, side views are presented of theplatform 100, hub 70, lock, cap 134 and connector 40 of the rightlateral and left medial ankle portions 62 (thus, FIGS. 6 through 9correspond to a mirror image of the exemplary embodiment shown in FIG.3). FIG. 6 illustrates the connector 40 with the centering pin 164engaged in the center bore 102. The key 178 is positioned at the opening118 of the receiving groove 110. The arm 182 of the key 178 extendsbetween the cap 134 and the platform 100 toward the hub periphery 108.The key 178 laterally stabilizes the connector 40 and also relieves thespindle 156 of torsional stresses.

In FIG. 7 it is seen that as the connector 40 is rotated toward thedeployed position 82, the key 178 impinges upon the edge 124 of thedeployment lock 122, urges the deployment lock 122 away from the hubperiphery 108, and slides between the deployment lock 122 and the hub70. In FIG. 8, the fin blade 20 has rotated to the deployed position(arrow 82). The key 178 is aligned with the angle-limiting notch 126,allowing the deployment lock 122 to return to its normal biased positionagainst the hub 70. With the deployment lock 122 so positioned, the key178 will not escape the notch 126, and the fin blade 20 will not rotatefrom the deployed position 82, unless the lock 122 is rotated by someforce such as the swimmer manipulating the handle portion 132. It willalso be appreciated that the lock edge 124 and the hub periphery 108,which includes the indentation 112, engage interlockingly to allow thehub 70 to support the lock when forces are applied to the fin blade 20.

With reference to FIG. 9, another exemplary embodiment of a diving finaccording to the present invention is shown. The angle-limiting notch126 is noticeably wider than the key 178. In contrast to the exemplaryembodiment shown in FIG. 8, which keeps the connector 40 very closelyaligned with boot longitudinal axis 74, this exemplary embodiment allowsthe connector 40 to wobble a few degrees either way while retaining itin the deployed position 82. In a preferred embodiment, the width of thenotch 126 and key 178 are selected such that the connector 40 deviatesup to 7.5° away from the boot longitudinal axis 74 in either direction.In another preferred embodiment, this range of deviation is 15°. Theadvantage of this feature is that, depending on the dimensions andflexibility of the fin blade 20, the blade angle can change quickly atthe beginning or end of a stroke in order to reach a propulsive anglenearly as soon as the stroke begins.

With reference to FIG. 10, another exemplary embodiment of a diving finaccording to the present invention is illustrated in which the boot 50is modified to fit the lower leg of a swimmer having a missing ormalformed foot. The fastener assembly 76 closes the front 52 of the boot50 about the distal portion of the swimmer's lower leg. The front 52,back 54 and sides 62 and 64 distribute stresses over a large area andsecure the boot 50 to the swimmer. It will be appreciated that thediving fin of the present invention does not require the swimmer to havea normally formed foot, nor even an articulated foot, in order to orientthe deployed blade 20 at a propulsive angle. As long as there issufficient limb and bone structure to stably support the boot 50, theswimmer can enjoy the advantages of the present invention.

The connector 40, spindle 156, cap 134, lock 122, hub 70, platform 100and centering pin 164 are likely to be subjected to extremes of stress,torque and abrasion. Therefore, these parts must be formed of a materialcombining stiffness, hardness, tensile strength and compressivestrength. A high-strength steel or other alloy is appropriate.Preferably, the material resists the corrosive effects of seawater.Preferably, dissimilar metals are not placed in electrical contact in amanner, which would tend to hasten corrosion. Depending on thedimensions and configuration of the parts, it may be feasible to formsome of the above parts of a composite, which includes, for example, aceramic, polymeric or fibrous material.

While the foregoing describes several embodiments of a diving fin inaccordance with the present invention, it is to be understood that theabove description is illustrative only and not limiting of the disclosedinvention. It will be appreciated that it would be possible for oneskilled in the art to modify a number of aspects of the fin blade 20,connector 40, cap 134, lock 122, hub 70, platform 100 and centering pin164. For example, different mounting mechanisms might be employed inplace of the spindle 156, receiving groove 110 and slot 140 set forthherein, so long as the claimed features are provided. Additionally, thedimensions set forth in the foregoing description are illustrative andmay be modified within the spirit of the invention. In particular, forexample, the dimensions of the hub 70, cap 134, bore 102 and spindle 156may be altered as needed to accommodate anticipated loads. Accordingly,the present invention is to be limited only by the claims as set forthbelow.

What is claimed is:
 1. A diving fin to be worn by a swimmer,comprising:a fin blade; a boot for coupling the fin blade to theswimmer, the boot having a top, a bottom, a front, a back, a medial sideand a lateral side, a boot longitudinal axis being defined by a linepassing through the top and bottom substantially parallel to the backand the sides; the fin blade being detachable to the boot; the bootbeing capable of positioning the attached fin blade parallel to the bootlongitudinal axis; and a hub affixed to the boot, a connector projectingfrom the fin blade, and the connector being lockably engageable with thehub, whereby the fin blade is held to the boot proximate the swimmer'sankle and projects past the swimmer's heel in line with the swimmer'slower leg and whereby the fin blade is readily attachable to anddetachable from the boot.
 2. A diving fin as set forth in claim 1,wherein the fin blade while attached to the boot has an undeployedposition wherein the attached fin blade is rotatably attached to theboot and a deployed position wherein the attached fin blade projectsfrom the boot substantially parallel to the boot longitudinal axis, theattached fin blade being rotatable from the undeployed position to thedeployed position and lockable in the deployed position,whereby, theswimmer may orient the fin blade away from the ground and walk freely.3. A diving fin as set forth in claim 2, wherein:the fin blade comprisesleading, trailing, medial and lateral edges and top and bottom surfacesand, a blade longitudinal axis being defined by a line intersecting theleading and trailing edges, a forward direction being defined as fromthe trailing edge to the leading edge, a blade transverse axis beingdefined by a line intersecting the medial and lateral edges andintersecting the longitudinal axis at a right angle; a boot transverseaxis is defined as a line passing approximately through the medial andlateral sides of the boot and intersecting the boot longitudinal axis ata right angle; and the fin blade when attached to the boot in thedeployed position is oriented away from the hub and past the bottom sothat the blade longitudinal axis is roughly aligned with the bootlongitudinal axis and the blade transverse axis is roughly parallel tothe boot transverse axis, whereby the deployed attached blade projectsfrom the hub past the swimmer's heel in substantial alignment with theswimmer's lower leg and the top and bottom surfaces of the fin bladeface the same directions as the swimmer's shin and calf, respectively.4. A diving fin as set forth in claim 3, wherein:at least one connectorprojects from the fin, the connector having a mating end; at least onehub is affixed to the boot, the hub and the mating end being lockinglyengageable; and the boot includes locking means, the locking meanskeeping the attached fin blade oriented in the deployed positionrelative to the boot.
 5. A diving fin as set forth in claim 3,wherein:at least one connector projects from the fin, the connectorhaving a mating end; at least one hub is affixed to the boot, the huband the mating end being lockingly engageable; and the hub includeslocking means, the locking means keeping the attached fin blade orientedin the deployed position relative to the boot.
 6. A diving fin as setforth in claim 3, wherein:the boot has a medial ankle portion and alateral ankle portion; a platform is affixed to each ankle portion, eachplatform having a substantially flat surface and a center bore centrallylocated in the surface, the center bore defining a hub axissubstantially parallel to the boot transverse axis; a hub is affixed toeach platform, the hub defining a flat base affixed to the platformsurface, a face opposite the base, a hub periphery, and groove in theface, the groove opening at the hub periphery, ending opposite thecenter bore and communicating with the center bore; a cap is affixed tothe ankle portion of the boot, the cap covering the hub face, the capdefining a cap periphery and a slot, the slot opening at the capperiphery, ending opposite the center bore and paralleling the groovetherebetween, the slot being narrower than the groove; and a medialconnector and a lateral connector project from the fin proximate theleading edge thereof, each connector having a mating end, each matingend defining a face and a backside; a spindle projects from eachconnector face, the spindle having a stem, a distal end which forms ahead, and a through bore running from the end to the backside, the headbeing dimensioned to enter sideways into the groove at the hub peripheryand to slide in the groove, the stem being dimensioned to enter sidewaysinto the slot at the cap periphery and to slide in the slot whileholding the head in the groove, the head being dimensioned to beconfined in the groove between the cap and the platform surface; and acentering pin is movably disposed in each through bore, the centeringpin being dimensioned to fit into the center bore while beingmanipulable at the backside of the mating end, the centering pin havinga locking position projecting into the center bore and a non-lockingposition withdrawn from the center bore, whereby the fin blade islockaby attachable to the boot.
 7. A diving fin as set forth in claim 6,further comprising angle limiting means for keeping the bladelongitudinal axis oriented in substantial alignment with the bootlongitudinal axis when the fin blade is attached to the boot in thedeployed position.
 8. A diving fin as set forth in claim 6, wherein theboot has a first angle limiting surface, the connector has a secondangle limiting surface and the first and second angle limiting surfacesare engageable to keep the blade longitudinal axis oriented insubstantial alignment with the boot longitudinal axis when the fin bladeis attached to the boot in the deployed position.
 9. A diving fin as setforth in claim 6, the connector has a first angle limiting surface, theankle portion of the boot has a second angle limiting surface and thefirst and second angle limiting surfaces are lockingly engageable tokeep the blade longitudinal axis substantially aligned with the bootlongitudinal axis when the fin blade is attached to the boot in thedeployed position.
 10. A diving fin as set forth in claim 6, wherein:akey projects from the connector; the ankle portion of the boot defines akeyway and a restraining mechanism; the key is slidable along the keywaywhen the connector is rotated between the deployed and undeployedpositions while attached to the boot; restraining mechanism and key arelockingly engageable when the connector is attached to the boot and inthe deployed position; and the key and restraining mechanism keep theconnector in the deployed position when so engaged.
 11. A diving fin asset forth in claim 6, wherein:the hub periphery defines a circularsurface having a hub radius about the hub axis; the cap peripherydefines a circular surface having a cap radius about the hub axis, thecap radius being greater than the hub radius such that the periphery ofthe cap overhangs the periphery of the hub; a spindle axis is defined asthe center of the through bore through the spindle and mating end; a keyprojects from the face of the connector approximately one cap radiusfrom the spindle axis; the key includes an arm projecting therefromtoward the spindle, the arm having an end approximately one hub radiusfrom the spindle axis; the key is slidably disposed proximate the capperiphery when the centering pin is engaged in the center bore, the armthen being slidably disposed proximate the hub periphery and between thecap periphery and the platform surface; a deployment lock is attached tothe ankle portion of the boot and defines an angle limiting surface sodisposed proximate the hub periphery as to lockingly engage the key whenthe connector is in the deployed position; whereby, when the connectoris in the deployed position, the centering pin and center bore cooperateto confine the key to the cap periphery, the cap periphery and platformsurface cooperate to confine the key arm therebetween and therebycooperate with the spindle head to stabilize the blade longitudinal axissubstantially perpendicular to the boot transverse axis, and the key anddeployment lock cooperate to limit the blade longitudinal axis to withina determined angle from the boot longitudinal axis as measured about theboot transverse axis.
 12. A diving fin as set forth in claim 11, whereinthe deployment lock has a locking position and a releasing position, ismovable therebetween and is biased in the locking position, the anglelimiting surface defines a notch, rotation of the connector from theundeployed position into the deployed position urges the deployment lockto the releasing position whereupon the notch receives the key, thedeployment lock returns to the locking position and the notch traps thekey, limiting the rotational position of the spindle relative to the hubto within a determined angle.
 13. A diving fin as set forth in claim 12,wherein the deployment lock is rotatably attached to the ankle portionof the boot.
 14. A diving fin as set forth in claim 13, wherein the capdefines an extension over the platform surface, a fastener connects theextension to the platform and the deployment lock is rotatably disposedabout the fastener.
 15. A diving fin as set forth in claim 11, furthercomprising a release manually operable to engage and disengage the keyand angle limiting surface.
 16. A diving fin as set forth in claim 3,wherein:first and second connectors project from the fin blade, eachconnector defining a mating end; first and second hubs are affixed tothe boot; each hub is lockingly engageable with a mating end so as tokeep the fin blade attached to the boot, and the boot includes lockingmeans, the locking means keeping the attached fin blade oriented in thedeployed position relative to the boot.
 17. A diving fin as set forth inclaim 3, wherein:first and second connectors project from the fin blade,each connector defining a mating end; first and second hubs are affixedto the boot; each hub is lockingly engageable with a mating end so as tokeep the fin blade attached to the boot, and the ankle portion of theboot includes locking means, the locking means keeping the attached finblade oriented in the deployed position relative to the boot.
 18. Adiving fin as set forth in claim 2, wherein, when the fin blade islocked in the deployed position, the blade longitudinal axis is confinedto within approximately 15° of parallel to the boot longitudinal axis ina plane roughly perpendicular to the boot transverse axis,whereby, thefin blade may readily assume a propulsive angle in the water at thebeginning and end of each kick.
 19. A diving fin as set forth in claim2, wherein, when the fin blade is locked n the deployed position, theblade longitudinal axis is confined to within approximately 7.5° ofparallel to the boot longitudinal axis in a plane roughly perpendicularto the boot transverse axis,whereby, the fin blade may readily assume apropulsive angle in the water at the beginning and end of each kick. 20.A diving fin as set forth in claim 1, wherein the hub defines a bore,the connector defines a spindle, the spindle is engageable with the hubat the bore, and the hub includes a locking means for keeping theconnector engaged at the bore.
 21. A diving fin as set forth in claim 1,wherein the hub has a face, the face has a bore, a periphery and agroove opening at the periphery and ending at the bore, a hub cap isaffixed to the boot, the hub cap covers the face, the hub cap has aperiphery and a slot, the slot opens at the hub cap periphery and endsover the bore;a spindle projects from the connector, the spindle isinsertable into the groove and slot, and while inserted therein is heldin the groove by the cap, and while held in the groove is slidable to aposition aligned with the bore; and a centering pin projects movablyfrom the spindle, the centering pin being insertable into the borewhereupon the centering pin locks the spindle in alignment with thebore, the centering pin being withdrawable from the bore to unlock thespindle from alignment with the bore, whereby, the swimmer mayapproximate the spindle to the groove at the periphery of the hub, slidethe spindle in the groove toward the bore, and insert the centering pininto the bore to lock the fin blade onto the boot.
 22. A diving fin tobe worn by a swimmer, comprising:a fin blade; a boot for coupling thefin blade to the swimmer, the boot having a top, a bottom, a front, aback, a medial side and a lateral side, a boot longitudinal axis beingdefined by a line passing through the top and bottom substantiallyparallel to the back and the sides; the fin blade being attachable tothe boot; the boot holding the attached fin blade in an orientationsubstantially dependent upon the orientation of the boot, whereby theblade is oriented independently of the elevation and extension of theswimmer's toes and the swimmer is able to kick powerfully andefficiently without hyperextension of the foot.
 23. A diving fin as setforth in claim 22, wherein the fin blade is detachable from the boot,whereby the swimmer may wear the boot without the fin blade and mayattach the fin blade to the boot while wearing the boot.
 24. A divingfin as set forth in claim 22, wherein the fin blade while attached tothe boot has an undeployed position wherein the attached fin blade isrotatably attached to the boot and a deployed position wherein theattached fin blade projects from the boot, in line with the bootlongitudinal axis, in a direction defined from the top of the boottoward the bottom of the boot, the attached fin blade being rotatablefrom the undeployed position to the deployed position and lockable inthe deployed position,whereby the swimmer may orient the fin blade awayfrom the ground to walk without tripping on the fin blade and may lockthe fin in the deployed position for swimming.
 25. A diving fin as setforth in claim 24, wherein:the fin blade comprises leading, trailing,medial and lateral edges and top and bottom surfaces, a bladelongitudinal axis being defined by a line intersecting the leading andtrailing edges, a forward direction being defined as from the trailingedge to the leading edge, a blade transverse axis being defined by aline intersecting the medial and lateral edges and intersecting thelongitudinal axis at a right angle; the boot defines a boot transverseaxis as a line passing approximately through the medial and lateralsides of the boot and intersecting the boot longitudinal axis at a rightangle; and the fin blade when attached to the boot in the deployedposition is oriented away from the hub and past the bottom so that theblade longitudinal axis is roughly aligned with the boot longitudinalaxis and the blade transverse axis is roughly parallel to the boottransverse axis, whereby the deployed attached blade projects from thehub past the swimmer's heel in substantial alignment with the swimmer'slower leg and the top and bottom surfaces of the fin blade face the samedirections as the swimmer's shin and calf, respectively.
 26. A divingfin as set forth in claim 25, wherein:at least one connector projectsfrom the fin, the connector having a mating end; at least one hub isaffixed to the boot, the hub and the mating end being lockinglyengageable; and the hub includes locking means, the locking meanskeeping the attached fin blade oriented in the deployed positionrelative to the boot.
 27. A diving fin as set forth in claim 25,wherein:first and second connectors project from the fin blade, eachconnector defining a mating end; first and second hubs are affixed tothe boot; each hub is lockingly engageable with a mating end so as tokeep the fin blade attached to the boot, and the boot includes lockingmeans, the locking means keeping the attached fin blade oriented in thedeployed position relative to the boot.
 28. A diving fin as set forth inclaim 23, wherein a hub is affixed to the boot, a connector projectsfrom the fin blade, and the connector is lockably engageable with thehub, whereby the fin blade is readily attachable to and detachable fromthe boot.